46 PEOF. G. B. HOWES AND MR. II. II. SWINNERTON ON THE 



quadrate. And in this connection it may be remarked that if the detailed configura- 

 tion of the cartilaginous upper jaw be a criterion of relationship, the fact that a near 

 approach to the condition occurring in Sphenodon is that of the Ca^cilian Ichthyophis 

 glutinosa as recently described by Winslow ^ is of great interest, when it is remembered 

 that these Apodal Batrachia, in the possession of dermal ossifications and other well- 

 known characters, are the most approximately Stegocephalian of all living forms ^. 



The Hyoicl and Columella auris. — Our observations concerning the hyoid apai-t from 

 its connection with the auditory apparatus are few. At the earliest stage we have 

 examined (viz. P) it has already appeared in procartilage in the form it assumes in the 

 adult, except for slight differences in general proportion, as is better seen at Stage Q 

 (PI. III. fig. 4). We have no evidence pointing to a compound origin of its basal 

 portion such as that described by Gaupp ^ for the Amphibian, or of the complexity in 

 structure of the order described by Siebenrock ^ for the Chelonia. 



It is only as concerning the vexed question of the relationship between the colu- 

 mella auris and the anterior cornu of the hyoid that we need proceed to details. The 

 nature of this in the adult has been so oft recapitulated that it will suffice to point 

 out once more that, apart from theories based on alternative interpretations of the 

 facts of adult anatomy and surmises necessary for their defence, the real question 

 developmentally at issue is whether or not the hyoid cornu and the extrastapedial are 

 secondarily united, and whether the object called by Huxley suprastapedial does or 

 does not arise independently. 



Huxley, in describing the parts of the adult, regarded^ the whole columellar 

 complex as hyoidean, and the extra- and suprastapedial processes as parts of its 

 expanded outer extremity. Peters, and all subsequent investigators ^, on the contrary, 

 mth the exception of Versluys, Avho has recently argued ^ in favour of original con 

 tinuity, have assumed that the connection between the extrastapedial and the hyoid 

 cornu is secondary, while Peters more especially believed the suprastapedial to have 

 been originally distinct. As great testimony to the extreme care with which Huxley 

 worked at this problem, there stands the fact that he drew attention {op. cit. p. 398) to 

 the presence, on the inner side of the foramen {f.h., text-fig. 11, which for brevity's 

 sake we associate with his name), of a fibrous differentiation included between the 

 extra- and suprastapedial processes. 



' Winslow, G. M. : Tuffs Coll. Stud. vol. i. no. 5, 1898, pi. iii. fig. 24. 

 " Cf. Boulenger, G. A. : P. Z. S. 1895, p. 402. 

 '^ Gaupp ,E. : Morph. Arbeiten, Jena, Bd. iii. 1894, p. 399. 

 ' Siebenrock, F. : Ann. naturhist. Hofmiis. Wien, Bd. siii. 1898, p. 4:24. 

 ' Huxley, T. H. : P. Z. S. 1869, p. 391. 



" Peters, W. : Monatsber. Akad. Wiss. Berlin, 1870, p. 15, and ibid. 1874, p. 40. Cf. also Baur, G. : Biol. 

 Centralbl. Bd. vi. 1887, p. 655 ; KUlian, G. : Jen. Zeitschr. Bd. sxiv. 1890, p. 649 ; Osawa, G.: 98 \ p. 520. 

 ' Versluys, Jan. : Zool. Jalirb. Anat. Abth. Bd. xii. 1899, p. 167. 



